1. Field of the Invention
This invention relates to a sheet sorter, and more particularly, for example, to a sheet post-processing apparatus used in distribution/accumulation and the like of sheet-like members (hereinafter termed a sheet), named copying paper, transfer paper or recording paper, discharged from an image forming apparatus, such as a copier, a printer or any other kind of recording apparatus, and to a sheet sorter for sorting, aligning and stapling the sheet.
2. Description of the Related Art
In general, a conventional sheet sorter having an aligning means includes an aligning reference wall for regulating an end portion of a sheet and a swinging arm for pushing an end of the sheet against the aligning reference wall. It performs alignment of the sheet by sequentially pushing copy sheets discharged from an image forming apparatus against the reference wall.
In some sheet sorters, a means for aligning sheets within bins of the sheet sorter is configured so that a swinging arm is threaded through part of a plurality of bins piled approximately perpendicularly to the plane of the floor, and sheets within all the bins can be aligned by the single swinging arm (the swinging arm threaded through the bins).
In the conventional sheet sorter, however, since alignment of sheets is performed by the arm a predetermined time after the sheets have been discharged into the bins facing a sheet discharge means, mountability of sheets is in some cases reduced according to the movement of the bins in normal sorting or reverse sorting after discharging the sheets.
More specifically, in normal sorting (the bins rise), no particular problem arises even if a sheet is aligned after the bins have shifted up when the number of sheets is small. However, when a large number of sheets are mounted and curling of the sheets is great, even if one end portion of a sheet receiving a pushing force by bins having a reduced interval between bins after the bins have shifted up is pushed by an aligning member, the other end portion of the sheet cannot be exactly aligned with the aligning reference wall, causing insufficient alignment of the sheets, or producing pressed marks, scars or the like on a pressed portion of the sheet, thus deteriorating quality of a copy.
In reverse sorting (the bins shift down), if a sheet is aligned by the aligning member and the bundle of copies (the bundle of sheets) are pushed by the aligning member and the aligning reference wall when the bins shift down, a pushing force is applied upon the bundle of copies, and the sheet might stop by the pressure of the aligning reference wall and the aligning member.